(CNN) -- Sitcom star Valerie Harper might not have much time left on Earth, but she is determined to live life to the fullest.
"I just want folks to see me, that I'm OK, that I'm not suffering so far," said Harper, who was recently diagnosed with a rare and terminal type of brain cancer. "There may be pain. There may be a lot of things ahead, but whatever they are, they're ahead. They're not now."
Harper, 73, is best known for playing Rhoda Morgenstern on "The Mary Tyler Moore Show," and its spinoff, "Rhoda." Like Harper in real life, Rhoda was outgoing and had a smile that lit up the screen.
The actress told CNN's "Piers Morgan Live" on Tuesday night that she feels good and hasn't had any side effects from treatment.
She said she is trying to live in the moment and had this advice: "Keep your chin up and don't go to the funeral, mine or yours or your loved ones, until the day of the funeral because then you miss the life that you have left."
News of Harper's illness was first reported by People magazine. It says she was told in January that she has leptomeningeal carcinomatosis, a condition in which cancer cells spread into the membranes that surround the brain and spinal cord.
Harpers' doctors say she could have as little as three months to live, People reported.
"The disease I have is quite a rare cancer and it is located in a limited area -- a very widespread area, but narrow. So a lot can happen if the cancer starts getting really aggressive, pressing on parts of the brain and causing me to lose either my speech or my ability to think, etc," Harper told Morgan.
But for now, she said, she is focused on putting one foot in front of the other, doing book tours, exercising, "just living my life."
"Death is out there for all of us," she said. "There's other ways to handle it than just sit on the couch and accept."
Harper previously battled lung cancer.
Leptomeningeal carcinomatosis, which is also known as neoplastic meningitis, affects approximately 5% of cancer patients, according to the Fox Chase Cancer Center in Philadelphia.
It is a difficult disease to treat because chemotherapy drugs often do not reach powerful enough concentrations in the membranes to be effective, the center said. Treatment can include radiation therapy and chemotherapy delivered straight to the spinal fluid.
"I have had a magnificent run -- the most wonderful husband in the world for 34 years, a great career," Harper said. "I really look at my life as blessed."